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Date:   Tue, 30 Apr 2019 10:22:25 -0700
From:   Jacob Pan <jacob.jun.pan@...ux.intel.com>
To:     Auger Eric <eric.auger@...hat.com>
Cc:     iommu@...ts.linux-foundation.org,
        LKML <linux-kernel@...r.kernel.org>,
        Joerg Roedel <joro@...tes.org>,
        David Woodhouse <dwmw2@...radead.org>,
        Alex Williamson <alex.williamson@...hat.com>,
        Jean-Philippe Brucker <jean-philippe.brucker@....com>,
        Yi Liu <yi.l.liu@...el.com>,
        "Tian, Kevin" <kevin.tian@...el.com>,
        Raj Ashok <ashok.raj@...el.com>,
        Christoph Hellwig <hch@...radead.org>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        Andriy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        jacob.jun.pan@...ux.intel.com
Subject: Re: [PATCH v2 19/19] iommu/vt-d: Add svm/sva invalidate function

On Tue, 30 Apr 2019 08:57:30 +0200
Auger Eric <eric.auger@...hat.com> wrote:

> On 4/30/19 12:41 AM, Jacob Pan wrote:
> > On Fri, 26 Apr 2019 19:23:03 +0200
> > Auger Eric <eric.auger@...hat.com> wrote:
> >   
> >> Hi Jacob,
> >> On 4/24/19 1:31 AM, Jacob Pan wrote:  
> >>> When Shared Virtual Address (SVA) is enabled for a guest OS via
> >>> vIOMMU, we need to provide invalidation support at IOMMU API and
> >>> driver level. This patch adds Intel VT-d specific function to
> >>> implement iommu passdown invalidate API for shared virtual
> >>> address.
> >>>
> >>> The use case is for supporting caching structure invalidation
> >>> of assigned SVM capable devices. Emulated IOMMU exposes queue
> >>> invalidation capability and passes down all descriptors from the
> >>> guest to the physical IOMMU.
> >>>
> >>> The assumption is that guest to host device ID mapping should be
> >>> resolved prior to calling IOMMU driver. Based on the device
> >>> handle, host IOMMU driver can replace certain fields before
> >>> submit to the invalidation queue.
> >>>
> >>> Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
> >>> Signed-off-by: Ashok Raj <ashok.raj@...el.com>
> >>> Signed-off-by: Liu, Yi L <yi.l.liu@...ux.intel.com>
> >>> ---
> >>>  drivers/iommu/intel-iommu.c | 159
> >>> ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 159
> >>> insertions(+)
> >>>
> >>> diff --git a/drivers/iommu/intel-iommu.c
> >>> b/drivers/iommu/intel-iommu.c index 89989b5..54a3d22 100644
> >>> --- a/drivers/iommu/intel-iommu.c
> >>> +++ b/drivers/iommu/intel-iommu.c
> >>> @@ -5338,6 +5338,164 @@ static void
> >>> intel_iommu_aux_detach_device(struct iommu_domain *domain,
> >>> aux_domain_remove_dev(to_dmar_domain(domain), dev); }
> >>>  
> >>> +/*
> >>> + * 2D array for converting and sanitizing IOMMU generic TLB
> >>> granularity to
> >>> + * VT-d granularity. Invalidation is typically included in the
> >>> unmap operation
> >>> + * as a result of DMA or VFIO unmap. However, for assigned device
> >>> where guest
> >>> + * could own the first level page tables without being shadowed
> >>> by QEMU. In
> >>> + * this case there is no pass down unmap to the host IOMMU as a
> >>> result of unmap
> >>> + * in the guest. Only invalidations are trapped and passed down.
> >>> + * In all cases, only first level TLB invalidation (request with
> >>> PASID) can be
> >>> + * passed down, therefore we do not include IOTLB granularity for
> >>> request
> >>> + * without PASID (second level).
> >>> + *
> >>> + * For an example, to find the VT-d granularity encoding for
> >>> IOTLB
> >>> + * type and page selective granularity within PASID:
> >>> + * X: indexed by iommu cache type
> >>> + * Y: indexed by enum iommu_inv_granularity
> >>> + * [IOMMU_INV_TYPE_TLB][IOMMU_INV_GRANU_PAGE_PASID]
> >>> + *
> >>> + * Granu_map array indicates validity of the table. 1: valid, 0:
> >>> invalid
> >>> + *
> >>> + */
> >>> +const static int
> >>> inv_type_granu_map[NR_IOMMU_CACHE_TYPE][NR_IOMMU_CACHE_INVAL_GRANU]
> >>> = {    
> >> The size is frozen for a given uapi version so I guess you can
> >> hardcode the limits for a given version.  
> > I guess I could, I just felt more readable this way.  
> >>> +	/* PASID based IOTLB, support PASID selective and page
> >>> selective */
> >>> +	{0, 1, 1},
> >>> +	/* PASID based dev TLBs, only support all PASIDs or
> >>> single PASID */
> >>> +	{1, 1, 0},
> >>> +	/* PASID cache */
> >>> +	{1, 1, 0}
> >>> +};
> >>> +
> >>> +const static u64
> >>> inv_type_granu_table[NR_IOMMU_CACHE_TYPE][NR_IOMMU_CACHE_INVAL_GRANU]
> >>> = {
> >>> +	/* PASID based IOTLB */
> >>> +	{0, QI_GRAN_NONG_PASID, QI_GRAN_PSI_PASID},
> >>> +	/* PASID based dev TLBs */
> >>> +	{QI_DEV_IOTLB_GRAN_ALL, QI_DEV_IOTLB_GRAN_PASID_SEL, 0},
> >>> +	/* PASID cache */
> >>> +	{QI_PC_ALL_PASIDS, QI_PC_PASID_SEL, 0},
> >>> +};    
> >> Can't you use a single matrix instead, ie. inv_type_granu_table
> >>  
> > The reason i have an additional inv_type_granu_map[] matrix is that
> > some of fields can be 0 but still valid. A single matrix would not
> > be able to tell the difference between a valid 0 or invalid field.  
> Ah OK sorry I missed that.
> >>> +
> >>> +static inline int to_vtd_granularity(int type, int granu, u64
> >>> *vtd_granu) +{
> >>> +	if (type >= NR_IOMMU_CACHE_TYPE || granu >=
> >>> NR_IOMMU_CACHE_INVAL_GRANU ||
> >>> +		!inv_type_granu_map[type][granu])
> >>> +		return -EINVAL;
> >>> +
> >>> +	*vtd_granu = inv_type_granu_table[type][granu];
> >>> +
> >>> +	return 0;
> >>> +}
> >>> +
> >>> +static inline u64 to_vtd_size(u64 granu_size, u64 nr_granules)
> >>> +{
> >>> +	u64 nr_pages;    
> >> direct initialization?  
> > will do, thanks  
> >>> +	/* VT-d size is encoded as 2^size of 4K pages, 0 for 4k,
> >>> 9 for 2MB, etc.
> >>> +	 * IOMMU cache invalidate API passes granu_size in bytes,
> >>> and number of
> >>> +	 * granu size in contiguous memory.
> >>> +	 */
> >>> +
> >>> +	nr_pages = (granu_size * nr_granules) >> VTD_PAGE_SHIFT;
> >>> +	return order_base_2(nr_pages);
> >>> +}
> >>> +
> >>> +static int intel_iommu_sva_invalidate(struct iommu_domain
> >>> *domain,
> >>> +		struct device *dev, struct
> >>> iommu_cache_invalidate_info *inv_info) +{
> >>> +	struct dmar_domain *dmar_domain = to_dmar_domain(domain);
> >>> +	struct device_domain_info *info;
> >>> +	struct intel_iommu *iommu;
> >>> +	unsigned long flags;
> >>> +	int cache_type;
> >>> +	u8 bus, devfn;
> >>> +	u16 did, sid;
> >>> +	int ret = 0;
> >>> +	u64 granu;
> >>> +	u64 size;
> >>> +
> >>> +	if (!inv_info || !dmar_domain ||
> >>> +		inv_info->version !=
> >>> IOMMU_CACHE_INVALIDATE_INFO_VERSION_1)
> >>> +		return -EINVAL;
> >>> +
> >>> +	if (!dev || !dev_is_pci(dev))
> >>> +		return -ENODEV;
> >>> +
> >>> +	iommu = device_to_iommu(dev, &bus, &devfn);
> >>> +	if (!iommu)
> >>> +		return -ENODEV;
> >>> +
> >>> +	spin_lock(&iommu->lock);
> >>> +	spin_lock_irqsave(&device_domain_lock, flags);    
> >> mix of _irqsave and non _irqsave looks suspicious to me.  
> > It should be in reverse order. Any other concerns?  
> I understand both locks are likely to be taken in ISR context so
> _irqsave should be called on the first call.
Yes, that is what i meant in reverse order.
	spin_lock_irqsave(&device_domain_lock, flags); 
	spin_lock(&iommu->lock);

then the unlocking part will remain the same.

> >>> +	info = iommu_support_dev_iotlb(dmar_domain, iommu, bus,
> >>> devfn);
> >>> +	if (!info) {
> >>> +		ret = -EINVAL;
> >>> +		goto out_unlock;
> >>> +	}
> >>> +	did = dmar_domain->iommu_did[iommu->seq_id];
> >>> +	sid = PCI_DEVID(bus, devfn);
> >>> +	size = to_vtd_size(inv_info->addr_info.granule_size,
> >>> inv_info->addr_info.nb_granules); +
> >>> +	for_each_set_bit(cache_type, (unsigned long
> >>> *)&inv_info->cache, NR_IOMMU_CACHE_TYPE) { +
> >>> +		ret = to_vtd_granularity(cache_type,
> >>> inv_info->granularity, &granu);
> >>> +		if (ret) {
> >>> +			pr_err("Invalid range type %d, granu
> >>> %d\n", cache_type,    
> >> s/Invalid range type %d, granu %d/Invalid cache type/granu
> >> combination (%d/%d)  
> > sounds good, indeed it is the combination that is invalid.  
> >>> +				inv_info->granularity);
> >>> +			break;
> >>> +		}
> >>> +
> >>> +		switch (BIT(cache_type)) {
> >>> +		case IOMMU_CACHE_INV_TYPE_IOTLB:
> >>> +			if (size && (inv_info->addr_info.addr &
> >>> ((BIT(VTD_PAGE_SHIFT + size)) - 1))) {
> >>> +				pr_err("Address out of range,
> >>> 0x%llx, size order %llu\n",
> >>> +					inv_info->addr_info.addr,
> >>> size);
> >>> +				ret = -ERANGE;
> >>> +				goto out_unlock;
> >>> +			}
> >>> +
> >>> +			qi_flush_piotlb(iommu, did,
> >>> mm_to_dma_pfn(inv_info->addr_info.addr),
> >>> +
> >>> inv_info->addr_info.pasid,
> >>> +					size, granu);
> >>> +
> >>> +			/*
> >>> +			 * Always flush device IOTLB if ATS is
> >>> enabled since guest
> >>> +			 * vIOMMU exposes CM = 1, no device IOTLB
> >>> flush will be passed
> >>> +			 * down. REVISIT: cannot assume Linux
> >>> guest
> >>> +			 */
> >>> +			if (info->ats_enabled) {
> >>> +				qi_flush_dev_piotlb(iommu, sid,
> >>> info->pfsid,
> >>> +
> >>> inv_info->addr_info.pasid, info->ats_qdep,
> >>> +
> >>> inv_info->addr_info.addr, size,
> >>> +						granu);
> >>> +			}
> >>> +			break;
> >>> +		case IOMMU_CACHE_INV_TYPE_DEV_IOTLB:
> >>> +			if (info->ats_enabled) {
> >>> +				qi_flush_dev_piotlb(iommu, sid,
> >>> info->pfsid,
> >>> +
> >>> inv_info->addr_info.pasid, info->ats_qdep,
> >>> +
> >>> inv_info->addr_info.addr, size,
> >>> +						granu);
> >>> +			} else
> >>> +				pr_warn("Passdown device IOTLB
> >>> flush w/o ATS!\n"); +
> >>> +			break;
> >>> +		case IOMMU_CACHE_INV_TYPE_PASID:
> >>> +			qi_flush_pasid_cache(iommu, did, granu,
> >>> inv_info->pasid); +
> >>> +			break;
> >>> +		default:
> >>> +			dev_err(dev, "Unsupported IOMMU
> >>> invalidation type %d\n",
> >>> +				cache_type);
> >>> +			ret = -EINVAL;
> >>> +		}
> >>> +	}
> >>> +out_unlock:
> >>> +	spin_unlock(&iommu->lock);
> >>> +	spin_unlock_irqrestore(&device_domain_lock, flags);    
> >> I would expect the opposite order  
> > yes, i reversed in the lock order such that irq is disabled.  
> spin_unlock_irqsave(&iommu->lock, flags);
> spin_lock(&device_domain_lock);
> ../..
> spin_unlock_irqrestore(&device_domain_lock);
> spin_unlock_irqrestore(&iommu->lock);
> ?
> 
I meant this:

	spin_lock_irqsave(&device_domain_lock, flags); 
	spin_lock(&iommu->lock);

...

	spin_unlock(&iommu->lock);
	spin_unlock_irqrestore(&device_domain_lock, flags);

> Thanks
> 
> Eric
> >>> +
> >>> +	return ret;
> >>> +}
> >>> +
> >>>  static int intel_iommu_map(struct iommu_domain *domain,
> >>>  			   unsigned long iova, phys_addr_t hpa,
> >>>  			   size_t size, int iommu_prot)
> >>> @@ -5769,6 +5927,7 @@ const struct iommu_ops intel_iommu_ops = {
> >>>  	.dev_disable_feat	= intel_iommu_dev_disable_feat,
> >>>  	.pgsize_bitmap		= INTEL_IOMMU_PGSIZES,
> >>>  #ifdef CONFIG_INTEL_IOMMU_SVM
> >>> +	.cache_invalidate	= intel_iommu_sva_invalidate,
> >>>  	.sva_bind_gpasid	= intel_svm_bind_gpasid,
> >>>  	.sva_unbind_gpasid	= intel_svm_unbind_gpasid,
> >>>  #endif
> >>>     
> >> Thanks
> >>
> >> Eric  
> > 
> > Thank you so much for your review. I will roll up the next version
> > soon, hopefully this week.
> > 
> > Jacob
> >   

[Jacob Pan]

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